“Because of their chromosomes, women have two copies of the ACE2 gene and men have only one copy," Oudit said. "This does not seem to make women more susceptible to COVID-19 infection, but it does protect them from the complications associated with the virus."
Oudit explained that ACE2 is an X chromosome-linked gene. To avoid duplication, one X chromosome tends to be inactivated, but due to its location ACE2 escapes inactivation, meaning women have twice as many active genetic instructions to make ACE2.
Another gene that is twice as strong in women due to this X-inactivation escape is called Toll-like receptor seven, a key part of the innate immune system.
"The stronger presence of Toll-like receptor seven in women explains why women's immune systems are stronger than men's and can tolerate virus infection better, including the common cold," Oudit said. "The man-cold phenomenon is real."
